Add AHAH information about a form element to the page to communicate with
javascript. If #ahah[path] is set on an element, this additional javascript is
added to the page header to attach the AHAH behaviors. See ahah.js for more
information.

In IE, if only one submit button is present, AND the enter key is
used to submit the form, no form value is sent for it and our normal
button detection code will never detect a match. We call this
function after all other button-detection is complete…

Performs validation on form elements. First ensures required fields are
completed, #maxlength is not exceeded, and selected options were in the
list of options given to the user. Then calls user-defined validators.